I'm working on a modification that will allow me to use time machine on OS X to backup directly to Tomato USB NAS
still haven't decided if i'll go for avahi or mDNS responder.. and netatalk is also planned for integration in the process

more info soon..
;)

edit:
netatalk requires some additional libs..
I don't like bloating the source tree with unnecessary software so I'll try to work out a solution without them…